A dynamic range narrows as the pixel miniaturization proceeds in an image sensor, such as a CMOS sensor, along with a demand for a higher pixel density of an image pickup apparatus. As the dynamic range narrows, the underexposure and luminance saturation are likely to occur in each of a shadow part and a highlighted part in a captured image and thus the image quality deteriorates.
In processing a captured image with a narrow dynamic range using a correction filter, such as a Wiener filter, information of luminance saturation part is not correctly acquired and a problem, such as ringing, is likely to occur.
Accordingly, each of Patent Literatures (“PLTs”) 1 and 2 proposes a method for acquiring a plurality of images with different exposures, for combining them with one another, and for acquiring a high dynamic range (“HDR”) image with an enlarged dynamic range.